Beat salt and egg whites with a mixer at high speed until foamy. Gradually add sugar, 1 tablespoon at a time, beating until stiff peaks form. Add mint; beat until blended.
Spoon mixture into a large zip-top plastic bag. Snip off a 1/2-inch opening in 1 bottom corner of bag. Pipe 108 (1-inch-round) mounds onto 3 parchment-lined baking sheets. Bake at 300° for 25 minutes or until dry. Cool on baking sheet 5 minutes. Remove from pan.